In recent years, in association with reduction of a space for installation of OA equipment as well as technological advance in minimizing various types of equipment and digital image technology, digital equipment has become more and more versatile, and a color digital image composing apparatus with multiple functions including a copy function, a facsimile function and a printer function has been developed and diffused.
However, in communications between systems treating images using the facsimile functions in the conventional type of color digital image composing apparatus as described above, what functions a partner system has can not be known before a communication line is established between two systems and communication is actually started. Even if the functions of the partner system has are known, a given document can be checked only by the sending side. For this reason, how the image is actually sent can not be checked by the sending side, and for instance, whether the image is printed by an image output device in the receiving side with ink or toner can not be checked, and thus transaction of image data most suited to capability of the receiving system is not executed.
In addition, for instance, when a color digital image composing apparatus is a stand-alone system, if any abnormality occurs in an image reading device, a portion thereof and the image reading device is exchanged with a new one, there would be no problem on the condition that the new one has the completely same functions as those of the previous one, but if there are any difference in specifications between the two devices, also characteristics of the entire apparatus become different, but actually communication by the facsimile function is executed without taking the change into considerations only by modifying the image data, transaction of image subjected to best correction is not always executed.
Especially, when a color digital image composing apparatus is constructed by assembling individual devices, change of each device is, different from a stand-alone system, very easy, and it is required to know characteristics and capability of each device each time component device is exchanged, which makes it furthermore difficult to execute best correction.